Environmental chemistry includes the analysis of soil samples to qualitatively and quantitatively determine presence of contaminants. Current analytical chemistry procedures are very time consuming and labor intensive, and will not realistically meet future needs generated by the U.S. Department Of Energy's environmental restoration and waste management programs.
Accurate soil sample analysis is a critical determination. Before remediation of problem areas can begin, the type and extent of contamination must be determined. Samples to be analyzed must be retrieved from the site and transported to a facility capable of analytical chemistry. The soil sample is processed to remove constituents that are not of interest and to isolate the contaminating substances. Once the sample has been processed and prepared, it is submitted for spectral analysis to determine content and concentration. Now, a trained scientist is required to determine if the concentration levels indicate contamination or are just indicative of background levels. As a precaution, spiked samples are processed with the actual sample. These spiked samples are used to verify that the process is yielding direct results and all must be analyzed the same way.
The protocol that includes all of the tasks from sample retrieval to output of characterization information has been designated as a standard analysis method, or SAM for short. If SAMs could be automated, laboratory technicians would be able to perform analytical analysis in a fraction of the time and cost of conventional prior art methods.
A SAM typically consists of three categories of operations: sample preparation, analysis, and data interpretation. Imbedded within the different areas of the SAM are many smaller tasks, such as weighing the sample or concentrate. Often these steps are repeated several times during the course of a SAM and are common to several SAMs. In accordance with an aspect of the invention, the equipment required to perform individual steps has been developed into automated modules.
Common to many SAMs are filtration and liquid concentration. This invention principally concerns methods and apparatus for filtering previously concentrated liquid samples. As a result of the typical concentration procedures, suspended solids precipitate out of the sample solution. To avoid equipment damage, these solids are filtered out of the sample. In the current procedure, a syringe is used to draw approximately 10 milliliters of sample through a filter. If the solids content is high, the filter holder must be disassembled to replace the paper filter and reassembled. Sometimes this must be performed three to four times per sample. It would be desirable to improve upon prior art techniques in liquid sample filtration.
Although this invention spawned from research associated with development of a standard laboratory module in conducting an overall automated process for analyzing test samples in accordance with EPA standards, those skilled in the art will find other uses of the invention which is intended to be limited only by the accompanying claims appropriated interpreted in accordance with the Doctrine of Equivalents.